SPDOS was marketed in the UK by Watford Electronics as a disk interface and operating system. Kempson later sold a version which used less RAM, approx. 700 bytes (Watford used about 8k). A variant of the SPDOS interface was marketed in North America by RAMEX International and known as the Millenia K.
This version was customized for Oliger hardware by Cuyahoga Valley Software Works.